1. Technical Field
The present invention relates to a pipeline lining method for lining a pipeline in order to repair an aging pipeline.
2. Background Art
In order to repair an aged sewer pipe or other pipeline buried under ground using already proposed pipeline lining methods without removing the pipe from the ground, a tubular lining material impregnated with a thermosetting resin is inserted into the pipeline, the lining material is heated while being expanded by air pressure or the like and pressed against an inner peripheral surface of the pipeline, and the thermosetting resin impregnated in the lining material is cured to line the pipeline. A method using vapor (water vapor) or a method using a hot water shower is used for heating the lining material.
When vapor is used in order to cure the lining material, high-temperature vapor is sprayed in a length direction of the pipe from one end part of the lining material that is inserted into the pipeline and pressed against the inner peripheral surface of the pipe to the inside of the lining material. The vapor fills the lining material, and heat from the vapor heats and cures the lining material.
On the other hand, a method is known from, e.g., Japanese Patent No. 2501048 in which curing is achieved by a hot water shower. In such a method, a hot water hose in which a plurality of spray openings for spraying hot water is formed at predetermined intervals in a length direction, is inserted into the pipeline along with the lining material. The lining material is expanded by air pressure, and high-temperature hot water is pressurized and supplied to the hot water hose while the lining material is pressed against the inner peripheral surface of the pipe. This causes hot water to be sprayed as a hot water shower from the spray openings of the hot water hose and blown against the inner peripheral surface of the lining material, thus heating and curing the lining material.
However, in a thermal curing method that uses vapor, the temperature decreases, the vapor condenses into water droplets and the amount of drippage thereof increases, as the sprayed vapor travels away from a nozzle. Therefore, drawbacks are presented in that the vapor is sparse in the vicinity of an end part of the lining material on the side opposite the nozzle, heat is insufficient, the thermosetting resin of the lining material is not readily cured, and the time required for the resin to cure increases. A problem is also presented in that uniform heating cannot be achieved in the length direction of the lining material. In order to address such problems, the amount of vapor sprayed from the nozzle must be increased, and a large amount of power must be provided for a heater or boiler for generating the vapor.
Problems related to poor efficiency are accordingly presented, and additional costs associated with fuel and the like are incurred.
As the pressure in the pipe increases, the temperature of the vapor also increases. Under normal pressure within the pipe, the temperature of the vapor increases from 150° C. to 170° C. For this reason, a problem is presented in that the characteristics of the resin of the lining material will be adversely affected.
On the other hand, in a method using a hot water shower, the hot water of the hot water shower sprayed as a shower against the inner peripheral surface of the lining material is ejected in a point-like profile, and does not spread. Therefore, problems are presented in that the lining material is not readily heated in a planar and uniform fashion and that the time required to cure the resin increases. For example, 20 to 100 spray openings for the hot water holes must be provided for every meter of hose in order to heat the lining material in as planar and uniform a fashion as possible. When the number of spray holes is increased, the amount of hot water consumed increases, efficiency is poor, and costs are incurred.